Inclinometer



June 23, 1925.

1,542,809 F. H. ALEXANDER ET AL I INCLINOMETER Ffii'ed Dec. 1, 1922 2 Sheets-Sheet 1 r a m s WW Mm /H S m. M m

June 23, 1925. 1,542,809

F. H ALEXANDER ET AL INCLINOMETER Filed Dec. 1, 1922 2 Sheets-Sheet 2 Patented June 23, 1925.- 5 L3 9 UNITED STATES PATENTOFFICE.

FRANCIS'HERBER'I. ALEXANDER, 0F NEWGASTLE-ON-TYNE, AND JOHN WILSON GILLIE, OF NORTH SHIELDS, ENGLAND. i

INOLINOIETER Application filed December 1, 1922. Serial No. 604,199.

To all whom it may com-em: terms may be provided to cause alternate Be it known that we, FRANCIS HERBERT excess and reductionin the magnetic couple l6 ALEXA DER, residing at 34 Burdon Terrace, as the short period pendulum deviates more Jesmond, Newcastle-on-Tyne, England, and and more from the normal.

JOHN WILSON GILLIE, of The New Quay, The short period pendulum may also North Shields, England, both subjects of carry a subsidiary magnet placed so as to His Majesty the King of Great Britain, assist in centralizing the long period pen- 00 have invented certain new and useful Imdulum against any frictional effect of the provements in or Relating to Inclinometers, bearings. I

10 of which the following isa specification, Means may be provided for adjusting the reference being had therein to the accomperiods of one or both of the pendulums. panying drawing. A combined datum line and collimating 66 This invention relates to inclinometers lens may be attached to the long period penand other instruments in which it is desired dulum when necessary, as for example when to indicate continuously a fixed direction, the pendulum is used for the purpose of such as the vertical, notwithstanding disprovidin an artificial horizon or similar .turbing accelerations, and has for its pridatum ane. 70 mary object to use magnetic means to cause The ong period pendulum may be supa pendulum of short period to oppose the ported in gimbals so as to move in two deflection of a pendulum of relatively long planes at right angles to each other, the period when subjected to acceleration, so said pendulum being provided with a systhat an accurate determination of the said tem of magnets and oo-operating short '15 I fixed direction may be obtained under disperiod pendulums for each of the two directurbing accelerations. tions of motion.

According to this invention a pendulum It is to be understood that the long period of relatively long period mounted upon the pendulum may be of any suitable kind or frame of the instrument is used to indicate construction, for example, a pendulum of a desired direction, such as the vertical, and the Mallock type, which oscillates in fluid a co-axial pendulum of short period is promay be employed.

to vided with a magnet placed in relation with Examples of construction according to another'magnet or armature upon the long the invention are illustrated in the annexed period pendulum, to form a magnetic coudrawings which are more or less diagram so pling between the two pendulums, the momatic in character and in which ment of which increases according to the Fig. 1 is a front elevation of an inclinom amount of relative deflection between the eter with most of the case shown in section. two pendulums. 1 Or, obviously, the 4 said Fig. 2 is a part sectional side elevation of magnetic coupling may be formed by a mag- Fig. 1 with the case in section. net on the long period pendulum and an Fig. 3 is a sectional plan of Fig. 1 along armature on the short period pendulum. a line 33 just above the axis.

40 The means for forming the said magnetic Fig. l'is an elevationof a modification.

coupling may be so arranged and the mag- Fig. 4 shows a detail. net or magnets of such strength that the Fig. 5 is a cross section on the line a.-.a 05 turning couple produced by a deflection of of Fig. 4. the short period pendulum, due to an 210- Fig. 6 is a plan of Fig. 4.

45 celeratio-n, counterbalances the turning Fig. 7 is a front elevation of another couple on the lon period pendulum promodification. duced by said aoce oration. Fig. 8 is an end elevation of Fig. 7.

The magnets, or the magnet and arma- Fig. 9 is a plan of Fig. 7. Y ture, may be attached to their respective Referring to Figs. 1 to 3 inclusive, which 50 pendulum-s so that the clearances between illustrates'a simple form of inclinometcr, a their poles may be adjusted in order that long period pendulum 1 is mounted on an the magnetic couple may be varied. axis 6 in bearings t, and a short period penl bmall additional subsidlary magnet sys- -dulum 2 is mounted on an axis 8 in bearings 9 co-axial with the axis 6. A magnet 3 is attached to the long period pendulum 1, and a magnet 4 to the short period ndulum 2,-so that their opposite poles a, and 0, d are equidistant and opposite one another in'the normal position. The ndulum 1 is provided with a datum point 11, and the pendulum 2 is provided with. a pointer 13 adapted to travel over the scale 14 which is upon pendulum 1.

The apparatus is mounted in a case 10 which is provided with a scale 12' in proximity to the path of the datum point 11, to show the inclination of the case. A glazed opening in the case 10 permits 11, 13 and 14 to be seen.

The magnet 4 is not in the same plane as the magnet 3 to permit a transverse. clearance 26 between them. There are also radial clearances 27 between the opposed poles of the magnets. The magnitude of these clearances may be varied or adjusted by suitable means to vary the magnitude of the magnetic torque.

The pendulum 1 is justable sliding weig t 5 to permit the period to be varied.

When a disturbing acceleration (say towards the right hand in Fig. 1) is present at the axis of suspension, the pendulum 2 deviates towards the left more rapidly than the pendulum 1. The resulting change in the relative positions of the two pendulums brings the poles a, b closer together and moves the poles c, d further apart. The attraction between aand b is therefore increased and between a, d diminished. There is therefore a resultant turning couple produced which affects both pendulums, tending to decrease the deviation of pendulum 1 and to increase that of pendulum 2. The amount of acceleration force on endulum 1 is small and can be counterb anced by the magnetic moment. The moment of the acceleration force on the pendulum 2 is rela- I tively large so that the increase of moment due to the magnetic moment is negligibly small.

By suitably ad'usti-ng the clearances 26, 27 to the strengt of the magnets and'by 'adjusting the period of the pendulum 1,

the magnitudes of the moments due to acceleration and to the magnetic attraction substantially counteracts each other on the pendulum 1 over a considerable range of deviation of the pendulum 2, so that the deviation of the pendulum 1 is made small for a considerable range of variation in the magnitude of acceleration.

Thus the inclination of the case is shown b means of the datum mark 11 and scale 12. 'Rhe magnitude of the disturbing acceleration is shown by means of the pointer 13 and scale 14.

In the modification shown in Figs. 1 to -matin lens 16 is attached to the pendulum operate with the magnet 18 for the purpose rovided with an ado 6 inclusive, the long period ndulum 1 is arranged as a horizontal unit aving adjustable balancing weights 5, 17 and bar magnets 3, and pivoted on a frame 10. The short period pendulum 2 is pivoted to the frame 10 co-axial with the pendulum 1 and is provided with magnets 4 co-operating with the magnets 3.

A datum line 15 combined with a colli- 1 sot at 15 may. be seen through'16 when the instrument is used, for example, to provide an artificial horizon or similar datum plane. I

Thependulum 1 may be provided with a subsidiary magnet 18 and the pendulum 2 with subsidia magnets 19 adapted to cooperate with t e magnet 18 to cause alternate excess and reduction in the magnetic couple as the pendulum 2 deviates more'and more from the normal. The pendulum 2 may also be provided with the subsidiary magnet 19 (see Fig. 4) adapted to ooassisting in centralizing the pendulum 1 against any frictional effect of the bearings.

In the modification shown in Figs. 7 to 9 inclusive, the pendulums 1 and 2 provided with the magnets 3 and 4 are pivoted in a frame 20 which latter is provided.- with pivots 21 at right angles to the axes of the pcndulums 1 and 2, so as to act as gimbals to allow the long period pendulum 1 two motions respectively at right angles to one another. The pivots 2d are mounted in. bearings 22 on a fixed frame or case 10. Geo rating magnets 23, 23 are mounted on .t e frame 20 and on secondary short period pendulums 2' respectively. The pendulums 2 oscillate in planes at right angles to the planes of oscillation of the pendulum 2.

' The frame 20 is counterbalanced by weights 24 adjusted by screws 25. These weights 24 and screws 25 are omitted from Figs. 7 and 9 for the sake of clearness.

In Fig. 4. ad'usting screw 28 enables pole of magnet 3 to varied as regards its angularor circumferential distance from that of ma et 4. In Fig. 7 adjusting screw 27 one les poles of magnet 23 to be varied as regards their transverse clearance from those of 23, which rotates in a plane parallel to that of 23.

By the above described construction the long period pendulum 1 may be compensated for disturbance by acceleration in two directions at right angles.

What we claim and desire to secure by Letters Patent of the United States is:-

1. An instrument of the character described, comprising in combination a pendulum of relatively long period, a pendulum of short period, and means between the two pendulums for forming a magnetic coupling to oppose the deflection of the long period pendulumwhen subjected to acceleration.

2. An instrument of the character described, comprising a frame for said instrument, a pendulum of relatively long period mounted in said frame of the instrument, to indicate a desired direction, such as vertical, a pendulum of short riod mounted co-axially with said first pendiilum,

and means for forming a magnetic coupling a between the two'pendululns comprising a m'agnet for one of the pendulums disposed in cooperative relation with a magnet upon the other pendulum, the resultant moment of said coupling being increased substantially in direct proportion to the amount of relative deflection between the two pendulums.

3. An instrument, as claimed in claim 2, in which the magnets attached to the two pendulums are disposed toswing in arallel planes having a desired clearance t erebe-, tween.

4. An instrument, as claimed in claim 2, in which the magnets attached to the two pendulums are disposed to swing in parallel planes, having a desired clearance therebetween and means to adjust the relative positioris of the magnets whereby the clearance between the elements may be varied to change the magnetic couple.

5. An instrument, as claimed in claim 2, including means forming a datum line attached to the long period pendulum, and a collima-tin lens carried by the latter, where by the sand line may be observed through the lens as for example when used as an artificial horizon.

6. An instrument as claimed in claim 2, in which the frame for the long-period pendulum comprises a supporting gimbal to enable freemovement of said pendulum in two planes at right angles one to the other, short-period pendulums associated with said gimbal, and ma ets carried by said gimbal and its associated pendulums, re-

spectively, said magnets being adapted to cooperate to oppose efiection of said gimbal in a plane normal to the plane of oscillation of said long-period pendulum.

In testimony whereof we have hereunto signed our names in the presence of two subscribing witnesses.

FRANCIS HERBERT ALEXANDER. JOHN WILSON GILLIE.

Witnesses:

H. F. RENNOLDSON, A. HILLARY. 

